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RNN VAD: LP residual optimized (part 2)

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The cross-correlation function in the anonimous namespace of
lp_residual.cc is used once as to compute auto-correlation coefficients.
Hence, it can be simplified (and renamed).

Note that the `RnnVadTest.LpResidualPipelineBitExactness` unit test
is still passing.

Bug: webrtc:10480
Change-Id: Ie769e42907c15572172a8ad1a34e82ce60c4a386
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/189962
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Reviewed-by: Sam Zackrisson <saza@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32464}
This commit is contained in:
Alessio Bazzica
2020-10-21 13:32:02 +02:00
committed by Commit Bot
parent cc40d8203a
commit 024d0157ab
1 changed files with 10 additions and 15 deletions
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25
modules/audio_processing/agc2/rnn_vad/lp_residual.cc
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@ -21,22 +21,17 @@ namespace webrtc {
namespace rnn_vad {
namespace {
// Computes cross-correlation coefficients between |x| and |y| and writes them
// in |x_corr|. The lag values are in {0, ..., max_lag - 1}, where max_lag
// equals the size of |x_corr|.
// The |x| and |y| sub-arrays used to compute a cross-correlation coefficients
// for a lag l have both size "size of |x| - l" - i.e., the longest sub-array is
// used. |x| and |y| must have the same size.
void ComputeCrossCorrelation(
// Computes auto-correlation coefficients for |x| and writes them in
// |auto_corr|. The lag values are in {0, ..., max_lag - 1}, where max_lag
// equals the size of |auto_corr|.
void ComputeAutoCorrelation(
rtc::ArrayView<const float> x,
rtc::ArrayView<const float> y,
rtc::ArrayView<float, kNumLpcCoefficients> x_corr) {
constexpr size_t max_lag = x_corr.size();
RTC_DCHECK_EQ(x.size(), y.size());
rtc::ArrayView<float, kNumLpcCoefficients> auto_corr) {
constexpr size_t max_lag = auto_corr.size();
RTC_DCHECK_LT(max_lag, x.size());
for (size_t lag = 0; lag < max_lag; ++lag) {
x_corr[lag] =
std::inner_product(x.begin(), x.end() - lag, y.begin() + lag, 0.f);
auto_corr[lag] =
std::inner_product(x.begin(), x.end() - lag, x.begin() + lag, 0.f);
}
}
@ -91,12 +86,12 @@ void ComputeAndPostProcessLpcCoefficients(
rtc::ArrayView<const float> x,
rtc::ArrayView<float, kNumLpcCoefficients> lpc_coeffs) {
std::array<float, kNumLpcCoefficients> auto_corr;
ComputeCrossCorrelation(x, x, {auto_corr.data(), auto_corr.size()});
ComputeAutoCorrelation(x, auto_corr);
if (auto_corr[0] == 0.f) { // Empty frame.
std::fill(lpc_coeffs.begin(), lpc_coeffs.end(), 0);
return;
}
DenoiseAutoCorrelation({auto_corr.data(), auto_corr.size()});
DenoiseAutoCorrelation(auto_corr);
std::array<float, kNumLpcCoefficients - 1> lpc_coeffs_pre{};
ComputeInitialInverseFilterCoefficients(auto_corr, lpc_coeffs_pre);
// LPC coefficients post-processing.